thePCI Portal

What are the risks of using “public” wifi?

What are the risks of “public” WiFi?  Its not a great question as we do not define what “public” means.  Some better questions are:

  • What are the risks of connecting to a WiFi network run by an attacker?
  • What are the risks of connecting to the same WiFi shared with attackers?
  • What are the risks of connecting to unencrypted WiFi (that maybe just uses a captive portal for authentication or acceptance of conditions)?

So, what can go wrong on these types of network?

  • People can hijack your name resolution mechanism changing the destination of your network traffic.
  • People can view and attempt to hijack your data connections to try view your data or manipulate your network traffic.
  • People can attack your computer.

P.S. None of these risks are unique to “public” wifi.  Its kind of an internet thing, but if you to connect to a malicious network, these attacks can be easier to implement.  Tricking your browser (or banking app) into thinking its connected to your bank when its connected to an attacker is not that easy thanks to the implementation of TLS encryption and server side authentication.

What can i do to “more safely” use public WiFi?

  • Keep your operating system patched. If its managed by your organization, there might not be much you can do about this 🙁
  • Keep all of your applications (including browser and email clients) patched.
  • Use the built in operating system firewall.
  • Windows 10 users:  When you connect to WiFi networks the first time, Windows 10 asks you if the network is TRUSTED or PUBLIC. If you classify the network as public, the Windows firewall will help protect your computer. You should declare all networks as PUBLIC unless you need to run services or map drives. This is very rare outside of corporate networks.  (Do other OS’s have a feature like this?)
  • Do NOT install apps that are internet “services”. Like FTP servers, Tor exit nodes, web servers, 3rd party antivirus agents, media servers like PLEX. Anything that accepts connections from other users and hosts.
    And if you do install apps like this, Windows will ask you if you want to accept connections from public networks or only private networks. Accepting connections from public networks is dangerous, avoid allowing this.
  • If a network does not ask for a password to connect, its not encrypted. This is typical of large hotel chains that rely upon you to login with a set of credentials AFTER connecting to the network. Use a little bit extra caution with these network types. Losing my Hilton Honors password isn’t too big a deal, but the hotels that want me to share my last name and room number over an unencrypted network make me shake my head. P.S. No VPN can help you in this situation either because the hotel will not let you connect to the VPN endpoint until AFTER your authentication/confirmation.
  • On your personal Windows computer, use the built in Microsoft Defender antivirus service NOT a third party antivirus or security product (you may not get a choice on your corporately managed device). In general, these third party products:
    • are more expensive than free
    • slow your PC more than defender.
    • take up more RAM/memory than defender.
    • expand your network footprint with additional listening services which can make your computer more vulnerable to attack.
    • have a bad history with vulnerabilities that put your computer at risk.

In their defense, some of them may detect slightly more viruses than defender.


For some reason, the people who sell VPN products and services think that running VPN software is the only safe way to connect to “public” networks.  The best reason to run VPN software on a public network is to hide your network traffic entirely from the network provider so they don’t know what websites and services you use (i.e. twitter, Reddit, etc).  Analyzing this type of network traffic can identify you and leak metadata.  Using a VPN doesn’t prevent this type of network and metadata analysis, it just moves the job from your network provider (who probably is not doing this) to your VPN service provider (who probably says they are not doing this).

What Does Norton think?  (other than you should use Norton VPN)

“everyday activities that require a login — like reading e-mail or checking your bank account — could be risky business on public Wi-Fi.”  (SL: No explanation why?)

“The problem with public Wi-Fi is that there are a tremendous number of risks that go along with these networks. While business owners may believe they’re providing a valuable service to their customers, chances are the security on these networks is lax or nonexistent.”  (SL: A tremendous number???  why dont you list them for us?  The 5 you do list aren’t really that worrisome to internet users today.)

Man-in-the-Middle attacks

Unless the attacker has a cert signed by a certificate authority (CA) that I trust for a hostname that I also trust, i don’t see how this works. (except for crappy sites that don’t have https like  And even if they do, they are wasting their talents by deploying it on a geographically constrained WiFi network.

Unencrypted networks

Uh, so what? this only matters for plaintext traffic. I don’t have any. Why do you?

Malware distribution (via software vulnerabilities)

Uh, is my private WiFi connection to the internet much different?

Snooping and sniffing

What?  How and why?  You mean they can break the WiFi encryption (if it exists) and look at my encrypted traffic?

Malicious hotspots

Uh, wouldn’t a twinned hotspot be more of a problem with private WiFi ?  What if we just assume that all public WiFi is malicious?  Give us details!!

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